1. Field of the Invention
Unless otherwise indicated herein, the description in this background section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section. The present disclosure relates to an image forming apparatus that has a print function and is capable of displaying a print preview on a screen.
2. Description of the Related Art
A typical printing system can display a print preview on a monitor screen.
Specifically, a bitmap image (image data) generated for printing by a printer apparatus is returned to a host computer, thereby enabling the print preview to be displayed on a monitor connected to the host computer.
According to such a printing system, a print result can be confirmed before execution of the printing.
Incidentally, the number of gradation levels of color per pixel that can be reproduced by a display device such as a monitor or a liquid crystal panel is larger than the number of gradation levels of the printer apparatus. In some instances, the number of gradation levels produced by the printer apparatus may be shown by increasing or decreasing dots.
For example, a printer apparatus generally known to output high gradation reproduces color tones normally by no more than 16 gradation levels (gradation values of 0 to 15) for each of the CMYK colors. Alternatively, the monitor can reproduce an abundance of colors by combining color values of as many as 256 gradation levels (gradation values of 0 to 255) for each of the RGB colors.
Therefore, assuming that it is desirable to print a high-gradation image, the typical printer apparatus generates image data for print output by lowering the gradation of the image. When the image data, with lowered gradation, is used to display the image for confirmation before printing, the print preview is displayed on the monitor screen with rough colors.
If the print preview can be generated while maintaining the gradation of an object, it is possible to faithfully reproduce the original color tones.
When a high-gradation image object is developed into bitmap data with its gradation maintained, an amount of data thereof becomes large. Therefore, it is necessary to increase the capacity of a memory corresponding thereto.
Further, high-gradation image data exceeding the output gradation cannot be used for print output as it is. Rather, at a time of printing, it is necessary to generate the image data for print output corresponding to the output gradation.
It should be noted that in order to save a memory usage amount, a method that uses the print preview having a low resolution is conceivable, but it is difficult to define a reference to which the resolution is lowered. Further, if the resolution is uniformly lowered for individual objects, reproducing the objects may be difficult depending on attributes of the respective objects.